Implant delivery and retrieval systems and methods

ABSTRACT

Implementations described and claimed herein provide systems and methods for delivering and retrieving a leadless pacemaker. In one implementation, a leadless pacemaker has a docking end, and the docking end has a docking projection extending from a surface. A docking cap has a body defining a chamber. A retriever has sheaths extending with lumens distally from the chamber. A snare extends between the lumens forming a first snare loop pointing in a first direction and a second snare loop pointing in a second direction with a docking space formed therebetween. The snare is movable between an engaged position and a disengaged position by translating the first snare wire and the second snare wire within the first snare lumen and the second snare lumen. The engaged position includes the first snare wire and the second snare wire tightened around the docking projection within the docking space.

FIELD

The present disclosure relates to leadless pacemakers and relateddelivery and retrieval systems and methods. More particularly, thepresent disclosure relates to systems and methods for loading a leadlesspacemaker onto a catheter system for delivery to or retrieval from animplant site.

BACKGROUND

Cardiac pacing by an artificial pacemaker provides an electricalstimulation of the heart when its own natural pacemaker and/orconduction system fails to provide synchronized atrial and ventricularcontractions at rates and intervals sufficient for a patient's health.Such antibradycardial pacing provides relief from symptoms and even lifesupport for hundreds of thousands of patients. Cardiac pacing may alsoprovide electrical overdrive stimulation to suppress or converttachyarrhythmias, again supplying relief from symptoms and preventing orterminating arrhythmias that could lead to sudden cardiac death.

Cardiac pacing by currently available or conventional pacemakers isusually performed by a pulse generator implanted subcutaneously orsub-muscularly in or near a patient's pectoral region. Pulse generatorparameters are usually interrogated and modified by a programming deviceoutside the body, via a loosely-coupled transformer with one inductancewithin the body and another outside, or via electromagnetic radiationwith one antenna within the body and another outside. The generatorusually connects to the proximal end of one or more implanted leads, thedistal end of which contains one or more electrodes for positioningadjacent to the inside or outside wall of a cardiac chamber. The leadshave an insulated electrical conductor or conductors for connecting thepulse generator to electrodes in the heart. Such electrode leadstypically have lengths of 50 to 70 centimeters.

Although more than one hundred thousand conventional cardiac pacingsystems are implanted annually, various well-known difficulties exist.For example, a pulse generator, when located subcutaneously, presents abulge in the skin that patients can find unsightly, unpleasant, orirritating, and which patients can subconsciously or obsessivelymanipulate. Even without persistent manipulation, subcutaneous pulsegenerators can exhibit erosion, extrusion, infection, and disconnection,insulation damage, or conductor breakage at the wire leads. Althoughsub-muscular or abdominal placement can address some concerns, suchplacement involves a more difficult surgical procedure for implantationand adjustment, which can prolong patient recovery.

A conventional pulse generator, whether pectoral or abdominal, has aninterface for connection to and disconnection from the electrode leadsthat carry signals to and from the heart. Usually at least one maleconnector molding has at least one terminal pin at the proximal end ofthe electrode lead. The male connector mates with a corresponding femaleconnector molding and terminal block within the connector molding at thepulse generator. Usually a setscrew is threaded in at least one terminalblock per electrode lead to secure the connection electrically andmechanically. One or more O-rings usually are also supplied to helpmaintain electrical isolation between the connector moldings. A setscrewcap or slotted cover is typically included to provide electricalinsulation of the setscrew. This briefly described complex connectionbetween connectors and leads provides multiple opportunities formalfunction.

Other problematic aspects of conventional pacemakers relate to theseparately implanted pulse generator and the pacing leads. By way ofanother example, the pacing leads, in particular, can become a site ofinfection and morbidity. Many of the issues associated with conventionalpacemakers are resolved by the development of a self-contained andself-sustainable pacemaker, or so-called leadless pacemaker.

Similar to active fixation implantable leads used with conventionalpulse generators, leadless pacemakers are typically fixed to anintracardial implant site by an actively engaging mechanism such as ascrew or helical member that threads into the myocardium. Leadlesspacemakers are often delivered to an intracardial implant site via adelivery system including a delivery catheter. Conventional deliverycatheter systems are typically long (e.g., approximately 42 mm orlonger), making navigation of the patient anatomy difficult andincreasing a footprint of the system at the implant site.

Some conventional delivery systems are tether based in which attachmentof the leadless pacemaker to the delivery catheter is dependent on thetether alignment. Once the tether alignment is lost, which may occur dueto system tolerances or anatomical interferences, among other factors,the leadless pacemaker may spontaneously release from the deliverycatheter. Such a spontaneous release may cause embolism, a need toretrieve the leadless pacemaker, and/or other patient risks. Retrievalmay be performed by removing the delivery catheter and introducing aretrieval catheter to remove the leadless pacemaker. The deliverycatheter system is generally different in structure and operation fromthe retrieval catheter system, which increases procedure time,complexity, and cost. If retrieval cannot be performed using a retrievalcatheter system, the leadless pacemaker is typically retrieved throughsurgery, further complicating the procedure. Moreover, implanting asecond leadless pacemaker into a patient often requires the use of asecond catheter delivery system, as many conventional catheter systemsfail to accommodate bed-side loading of leadless pacemakers onto apreviously used catheter system. Instead, many conventional cathetersystems are preloaded during manufacturing. It is with theseobservations in mind, among others, that the presently disclosedtechnology was conceived and developed.

SUMMARY OF THE DISCLOSURE

Implementations described and claimed herein address the foregoingobservations by providing systems and methods for delivering andretrieving a leadless pacemaker. In one implementation, a leadlesspacemaker has a docking end, and the docking end has a dockingprojection extending from a surface. A docking cap has a body defining achamber. The docking cap has a proximal opening into the chamber, andthe proximal opening is coaxial with a longitudinal axis of a lumen of acatheter. A retriever has a first sheath and a second sheath extendingdistally from the chamber. The first sheath has a first lumen, and thesecond sheath has a second lumen. A snare includes a first snare wireand a second snare wire. The first snare wire extends from the firstsnare lumen into the second snare lumen forming a first snare looppointing in a first direction, and the second snare wire extends fromthe first snare lumen into the second snare lumen forming a second snareloop pointing in a second direction different from the first direction.The first snare loop and the second snare loop form a docking space. Thesnare is movable between an engaged position and a disengaged positionby translating the first snare wire and the second snare wire within thefirst snare lumen and the second snare lumen. The engaged positionincludes the first snare wire and the second snare wire tightened aroundthe docking projection within the docking space.

In another implementation, a docking cap has a body defining a chamber.A retriever has a first sheath and a second sheath extending distallyfrom the chamber. The first sheath is disposed at a position radiallyopposite to the second sheath relative to a central axis. The firstsheath has a first lumen, and the second sheath has a second lumen. Asnare includes a first snare wire and a second snare wire. The firstsnare wire extends from the first snare lumen into the second snarelumen forming a first snare loop having a first peak at the centralaxis. The second snare wire extends from the first snare lumen into thesecond snare lumen forming a second snare loop having a second peak atthe central axis. The snare is movable between an engaged position and adisengaged position by translating the first snare wire and the secondsnare wire within the first snare lumen and the second snare lumen. Thetranslation of the first snare wire and the second snare wire move thefirst peak radially inwards toward the second peak to the engagedposition and radially outwards away from the second peak to thedisengaged position.

In yet another implementation, a docking space is disposed relative to adocking projection extending from a surface of a body of a leadlesspacemaker. The docking space is formed by a first snare loop pointing ina first direction and a second direction different than the firstdirection. The first snare loop is formed from a first snare wireextending from a first snare lumen of a first sheath into a second snarelumen of a second sheath. The second snare loop is formed from a secondsnare wire extending from the first snare lumen of the first sheath intothe second snare lumen of the second sheath. The first snare loop andthe second snare loop are advanced over the leadless pacemaker until thedocking projection is disposed in the docking space. A size of thedocking space is decreased by retracting the first snare wire and thesecond snare wire into the first snare lumen and the second snare lumenuntil the first snare wire and the second snare wire tighten around thedocking projection. The first sheath and the second sheath are retractedinto a lumen of a catheter until the docking projection is positionedwithin a chamber of a docking cap.

In still another implementation, a leadless pacemaker has a docking end,and the docking end having a docking projection extending from asurface. A docking cap has a body defining a chamber. The docking caphas a proximal opening into the chamber. The proximal opening is coaxialwith a longitudinal axis of a lumen of a catheter. A retriever has aflexible grasper with a first arm disposed opposite a second arm. Eachof the first arm and the second arm form a hinge biased radiallyoutwards from the longitudinal axis. The docking cap locks the first armand the second arm on the docking projection when the body is sheathedover the retriever until the flexible grasper is disposed within thechamber.

In another implementation, a flexible grasper is disposed relative to adocking projection extending from a surface of a body of a leadlesspacemaker. The flexible grasper has a first arm disposed opposite asecond arm. Each of the first arm and the second arm forms a hingebiased radially outwards from a longitudinal axis. The dockingprojection is posited between the first arm and the second arm. A bodyof a docking cap is sheathed over the flexible grasper. The docking caplocks the first arm and the second arm on the docking projection by oneor more cap surfaces disposed relative to the chamber displacing thefirst arm and the second arm radially inwards holding the first arm andthe second arm in compression around the docking projection.

In yet another implementation, a leadless pacemaker has a docking end,and the docking end has an opening defined in a surface. A retriever hasa first arm disposed opposite a second arm around a central lumen. Eachof the first arm and the second arm forms a hinge biased radiallyinwards towards the central lumen. The first arm and the second arm aredisplaceable radially outwards by a mandrel translated through thecentral lumen towards the docking end. The radial outward displacementof the first arm and the second arm engages the surface of the dockingend within the opening.

Other implementations are also described and recited herein. Further,while multiple implementations are disclosed, still otherimplementations of the presently disclosed technology will becomeapparent to those skilled in the art from the following detaileddescription, which shows and describes illustrative implementations ofthe presently disclosed technology. As will be realized, the presentlydisclosed technology is capable of modifications in various aspects, allwithout departing from the spirit and scope of the presently disclosedtechnology. Accordingly, the drawings and detailed description are to beregarded as illustrative in nature and not limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic medial-lateral cross-section of a patient heartillustration an example cardiac pacing system having one or moreleadless pacemakers.

FIG. 2 shows an example catheter system for delivering and/or retrievinga leadless pacemaker.

FIG. 3 is a detailed view of a distal end of the catheter system.

FIGS. 4A-4C each show a retriever in a docked position with a leadlesspacemaker with FIGS. 4B and 4C being side and top views, respectively,and showing a docking cap transparent.

FIG. 5 depicts example movement of a flexible element, such as a torqueshaft or a catheter.

FIGS. 6 and 7 illustrate a side view and a perspective view of theretriever releasing or capturing the leadless pacemaker.

FIG. 8 shows the retriever in the form of an example of a flexiblegrasper adapted to open radially to release the leadless pacemaker.

FIG. 9 shows the retriever in the form of another example of a flexiblegrasper adapted to hinge laterally to release the leadless pacemaker.

FIGS. 10A and 10B depict a perspective view and a back view,respectively, of an example docking end of a leadless pacemaker.

FIG. 11 illustrates an example flexible grasper engaged to a dockingprojection of a leadless pacemaker.

FIG. 12 shows a perspective front view of an example docking cap.

FIG. 13 shows a docking end of a leadless pacemaker with example keysdefined in a surface.

FIGS. 14A and 14B are perspective and top views, respectively, of anexample docking projection having a cross shape.

FIG. 14C illustrates a flexible grasper engaged to the dockingprojection of FIGS. 14A-14B.

FIGS. 15A-15C show examples of the docking projection with a roundsurface.

FIGS. 16A and 16B illustrate a perspective view and a top view,respectively, of an example set of keys defined in a surface of thedocking projection.

FIGS. 17A and 17B show a top view and a perspective view of an exampleleadless pacemaker having a round docking projection with a set of keys.

FIG. 18 depicts an example docking cap disposed relative to an exampleleadless pacemaker, the docking cap including one or more cap surfacesconfigured to mating engage one or more docking surfaces of the dockingprojection.

FIGS. 19A and 19B illustrating an example docking cap released from andengaged to a leadless pacemaker, respectively, the docking cap having anovermolding configured to transfer torque via increased friction betweenthe docking cap and the leadless pacemaker.

FIG. 20 illustrates another example retriever in the form of a flexiblegrasper engagable to a docking button.

FIG. 21 is a cross-section of a docking cap holding arms of a flexiblegrasper in compression around a docking button within a chamber.

FIG. 22 is a detailed view of an example flexible grasper.

FIG. 23 shows a tether extending through a lumen of an example flexiblegrasper.

FIG. 24 depicts an example docking cap.

FIGS. 25A and 25B illustrate a rigid docking button and a flexibledocking button, respectively.

FIG. 26A shows a flexible grasper disposed relative to a docking buttonof a leadless pacemaker.

FIG. 26B illustrates the docking button positioned between a first armand a second arm of the flexible grasper.

FIG. 26C shows a docking cap sheathed over the flexible grasper andholding the first arm and the second arm in compression around thedocking button.

FIG. 27 illustrates an example docking projection having a loopconfigured to receive a tether, a snare, or a cable.

FIG. 28 is a cross-section of a retriever engaging a surface of adocking end of a leadless pacemaker within an opening in the surface.

FIG. 29 shows a retriever having inwardly biased arms.

FIGS. 30A and 30B show an example retriever in the form of a snareextending from a set of sheaths.

FIGS. 31A and 31B show detailed views of example snares.

FIG. 32 illustrates an example docking space disposed relative to adocking projection of a leadless pacemaker.

FIG. 33A shows the snare advanced over the leadless pacemaker with thedocking projection disposed in the docking space.

FIG. 33B illustrates the snare tightened around the docking projectionin an engaged position.

FIG. 34 is a detailed view of the snare tightened around the dockingprojection in the engaged position.

FIG. 35 illustrates movement of the leadless pacemaker relative to alongitudinal axis of the catheter in the engaged position.

FIG. 36 shows the leadless pacemaker docked to the docking cap.

FIG. 37 illustrates an example docking cap having a first tracker and asecond tracker.

FIG. 38 is a cross-section of a retriever in the form of a snaredisposed in a chamber of a docking cap.

FIGS. 39 and 40 are each a cross-section of a distal end of a cathetersystem showing a snare engaged to a docking projection of a leadlesspacemaker.

FIG. 41 shows a front view of the retriever in the form of a hingedgrasper engaged to a slotted docking projection of a leadless pacemakerand displaceable with a push-pull actuator, with a docking cap showntransparent.

FIG. 42 shows a side view of the hinged grasper of FIG. 41.

FIG. 43 is a detailed perspective view of the hinged grasper of FIG. 41shown with the arms of the hinged grasper also transparent.

FIG. 44 shows a front view of the retriever in the form of anotherhinged grasper engaged to a polygonal docking projection of a leadlesspacemaker and displaceable with a push-pull actuator, with a docking capshown transparent.

FIG. 45 shows a side view of the hinged grasper of FIG. 44.

FIG. 46 is a detailed perspective view of the hinged grasper of FIG. 44shown with the arms of the hinged grasper also transparent.

DETAILED DESCRIPTION

Aspects of the present disclosure involve systems and methods fordelivering and retrieving a leadless biostimulator, such as a leadlesspacemaker. Generally, the leadless pacemaker is delivered and retrievedfrom an implant location in a patient using a catheter system. Thepresently disclosed systems and methods thus facilitate repeatedimplantation and/or retrieval of leadless pacemakers via a singlecatheter delivery and retrieval system, thereby reducing waste and thecosts associated therewith. Additionally, the systems and methodsdescribed herein permit a single catheter system to deliver and retrievedifferent leadless pacemakers having varying configurations furtherreducing the operation burden of stocking multiple systems applicable tothe various configurations.

In one aspect, the catheter system includes a retriever in the form of agrasper, a snare, and/or the like, releasably engagable to a docking endof the leadless pacemaker to provide torque transmission to the leadlesspacemaker during deployment, as well as providing the engagement,delivery, detachment, and/or retrieval of the leadless pacemaker. Theretriever reduces the risk of spontaneous or otherwise undesired releaseof the leadless pacemaker from the catheter during delivery orretrieval. Moreover, the retriever provides reliable detachmentindependent of a relative position of a dual-tether system and isolatesrotation forces of the leadless pacemaker from the catheter system,which may otherwise cause binding and/or torque-wind in a dual-tethersystem. Tool-less, bed-side loading is facilitated with the presentlydisclosed technology, permitting the deployment of multiple leadlesspacemakers into the patient anatomy with reduced tissue trauma to thepatient anatomy during deployment due to the radial opening of theretriever.

The systems and methods described herein generally relate to a loadingtool having a retriever for releasably engaging a docking projection ofa medical implant, as well as to methods of delivering and retrievingthe same. While the present disclosure is discussed with reference toleadless cardiac pacemakers and torque as a loading technique, it willbe appreciated that the presently disclosed technology is applicable toother biostimulators and/or medical implant systems and methods as wellas loading techniques.

To begin a detailed description of an example cardiac pacing system 100having one or more leadless pacemakers 104, reference is made to FIG. 1.The leadless pacemakers 104 may each be configured for temporaryleadless pacing of a patient heart 102. In one implementation, each ofthe leadless pacemakers 104 is configured for placement on or attachmentto the inside or outside of a cardiac chamber, such as the right atriumand/or right ventricle, of the patient heart 102. The leadlesspacemakers 104 may be attached to cardiac tissue of the patient heart102, for example, via a helical anchor 106 that is threaded through themyocardium. It will be appreciated, however, that other primary fixationmechanisms, as well as secondary fixation mechanisms in some cases, maybe used to attach the leadless pacemaker 104 to tissue or otherwiserestrict movement of the leadless pacemaker 104 during implantation.

The leadless pacemakers 104 are delivered to and/or retrieved from thepatient heart 102 using a catheter system 108, as shown in FIG. 2.Generally, the catheter system 108 releasably engages the leadlesspacemaker 104 for intravenous advancement into the patient heart 102.The catheter system 108 engages the leadless pacemaker 104 in such amanner as to facilitate fixation to cardiac tissue, for example, usingthe helical anchor 106. As described herein, where the fixationmechanism engages the cardiac tissue through rotation, such as with thehelical anchor 106, the catheter system 108 is adapted to provide torquetransmission to the leadless pacemaker 104. Stated differently, thecatheter system 108 engages features of the leadless pacemaker 104 toapply torque to the leadless pacemaker 104 to screw the helical anchor106 into cardiac tissue.

The catheter system 108 engages the leadless pacemaker 104 at a distalend 110 and includes a handle at a proximal end 112 for directing thedelivery and/or retrieval of the leadless pacemaker 104. In oneimplementation, the catheter system 108 includes a torque shaft 114, asleeve 116, and an introducer sheath 120. The catheter system 108 mayalso include a steerable catheter 116 for deflecting the catheter system108 and/or one or more flush ports 128 and 130 for flushing saline orother fluids through the catheter system 118.

The torque shaft 114 provides torque transmission to the leadlesspacemaker 104 from the steerable catheter 118 and otherwise directsmovement of the leadless pacemaker 104 as controlled by one or moresteering knobs (e.g., a first steering knob 124 and a second steeringknob 126) disposed on a handle body 122. The introducer sheath 120 canbe advanced distally over the steerable catheter 118 to provideadditional steering and support for the steerable catheter 118 duringdelivery and/or retrieval and to surround the leadless pacemaker 104 asit is introduced through a trocar or introducer into the patientanatomy. Similarly, the sleeve 116 is movable along the steerablecatheter 118 and may be displaced distally over the leadless pacemaker104 to cover the torque shaft 114, the leadless pacemaker 104, and thehelical anchor 106 to protect patient tissue and anatomy during deliveryand/or retrieval.

Turning to FIG. 3, a detailed view of the distal end 110 of the cathetersystem 118 is shown. In one implementation, the steerable catheter 118extends through a sleeve cap 134 into the sleeve 116 where it is engagedto the torque shaft 114. The sleeve 116 may be displaceable over thetorque shaft 114 and leadless pacemaker 104 such that the leadlesspacemaker 104 is within the sleeve 116 proximal to a distal edge 132 ofthe sleeve 116. The sleeve 116 may also be steerable.

In one implementation, a distal end of the torque shaft 114 is engagedto a docking cap 136, which is configured to releasably engage theleadless pacemaker 104. The torque shaft 114 and the docking cap 136each deliver torque to the leadless pacemaker 104 during delivery and/orretrieval. FIGS. 4A-4C illustrate the catheter system 108 in a docked orengaged position with the docking cap 136 sheathed over a docking end ofthe leadless pacemaker 104. In one implementation, the docking cap 136includes a body 138 and a receiving portion 140 configured to engage adistal end 146 of the torque shaft 114. The distal end 146 of the torqueshaft 114 may remain rigidly attached to the receiving portion 140during use.

The body 138 of the docking cap 136 defines a chamber 142. As can beunderstood from FIGS. 4B-4C, a docking projection 148 extending from thedocking end of the leadless pacemaker 104 is disposed within the chamber142 in the docked position. A retriever 144 is displaceable within alumen of the torque shaft 114 and configured to releasably engage thedocking projection 148. More particularly, the retriever 144 isextendable through the body 138 of the docking cap 136 for placementrelative to the docking projection 148, and the body 138 of the dockingcap 136 is sheathed over the docking projection 148 causing theretriever 144 to capture the docking projection 148 within the chamber142.

In the docked position, the catheter system 108 provides torquetransmission to the leadless pacemaker 104. FIG. 5 illustrates thatduring a test mode or to reposition or otherwise manipulate the leadlesspacemaker 104 during deployment, the torque shaft 114 is torqueable andadjustable with a freedom of movement in a plurality of directions. Thetorque shaft 114 may be flexible and/or made from a variety ofmaterials. For example, the torque shaft 114 may be made from a polymer,metal, and/or the like. The torque shaft 114 may be made with a catheterlamination construction, formed as a hollow helical cable, and/or inother configurations for torque transmission and steering. In oneimplementation, the torque shaft 114 and/or the steerable catheter 118is a hypo tube. In other implementations, the torque shaft 114 and/orthe steerable catheter 118 includes a cable tube, a laser cut tube, anextrusion, a wire, a wire cable, and/or the like for increasedflexibility.

As can be understood from FIG. 6, the docking cap 136 is displaceableover the retriever 144 to cause the retriever 144 to move between anengaged position where the retriever 144 is engaged to the dockingprojection 148 within the chamber 142 and the catheter system 108 isdocked to the leadless pacemaker 104 and a disengaged position where theretriever 144 is disposed in its natural state outside the chamber 142and disengaged from the docking projection 148. As shown in FIGS. 6 and7, in one implementation, the docking cap 136 is retracting proximallycausing the retriever 144 to open radially to its natural state, therebyreleasing the docking projection 148 and disengaging the leadlesspacemaker 104. To recapture the leadless pacemaker for retrieval,repositioning, and/or the like, the retriever 144 is positioned relativeto the docking projection 148 and the docking cap 136 is sheathed overthe retriever 144 causing the retriever 144 to close radially over thedocking projection 148 within the chamber 142.

In one implementation, the retriever 144 is a flexible grasper with afirst arm disposed opposite a second arm that each form a hinge biasedradially outwards from a longitudinal axis of the retriever 144. Stateddifferently, the retriever 144 is biased open in its natural state infree space, as shown in FIGS. 6 and 7. In one implementation, thenatural state of the retriever 144 provides an opening defined by thearms with an inner diameter that is larger than a diameter of thedocking projection 148 and in some examples a body of the leadlesspacemaker 104. The retriever 144 in the form of a flexible grasper maybe made from a variety of elastic or otherwise flexible materials,including, but not limited to, Nitinol or other memory wire, cable,tubing, and/or the like.

As can be understood from FIGS. 4A-7, the docking cap 136 translatesaxially over the retriever 144 to move the catheter system 108 betweenthe docked and released positions. In one implementation, the body 138of the docking cap 136 includes one or more cap surfaces disposedrelative to the chamber 142. The cap surfaces displace the arms of theretriever 144 radially inwards to hold the arms in compression aroundthe docking projection 148. As such, the docking cap 136 and the dockingend of the leadless pacemaker 104 are configured such that the retriever144 remains locked on the docking projection 148 when the docking cap136 is sheathed over the retriever 144. This docked position facilitatesdelivery through the patient anatomy to a target location in the patientheart 102 for implantation. Once implanted, the docking cap 136 isretracted proximally, allowing the arms of the retriever 144 to openradially outwards to the natural state and thereby releasing the dockingprojection 148. The catheter system 108 is then removed from thepatient. The docking projection 148 may be recaptured for retrieval orrepositioning by sheathing the docking cap 136 over the retriever 144.During release and capture, tugging on or trauma to patient tissue isreduced or eliminated with the radial movement of the arms of theretriever 144 between the engaged and disengaged positions.

FIGS. 8 and 9 show examples of the retriever 144 in the form of aflexible grasper with a first arm 200 and a second arm 202 each forminga flexible loop attached to one or more mandrels extending through alumen of the torque shaft 114. In one implementation, the first arm 200includes one or more elongated bodies (e.g., a first elongated body 206and a second elongated body 208). The first elongated body 206 mayextend parallel to the second elongated body 208 within a first planewith a gap formed therebetween. A set of tapering portions connect theone or more elongated bodies to a set of grasping portions. In oneimplementation, a first grasping portion 214 is connected to the firstelongated body 206 with a first tapering portion 210 on the first plane,and a second grasping portion 216 is connected to the second elongatedbody 208 with a second tapering portion 212 on the first plane. Thefirst grasping portion 214 is generally parallel to the second graspingportion 216 and the first and second elongated bodies 206 and 208. Adistance between the first and second grasping portions 214 and 216 islarger than a distance between the first and second elongated bodies 206and 208, such that the first and second tapering portions 210 and 212extend inwardly from the first and second grasping portions 214 and 216to the first and second elongated bodies 206 and 208. The flexible loopof the first arm 200 is formed by a first looped portion 218 extendingalong a curve between the first and second grasping portions 214 and216.

The second arm 202 may mirror the first arm 200. In one implementation,the second arm 202 includes one or more elongated bodies (e.g., a thirdelongated body 220 and a fourth elongated body 222). The third elongatedbody 220 may extend parallel to the fourth elongated body 222 within asecond plane with a gap formed therebetween. The second plane isparallel to the first plane. A second set of tapering portions connectthe one or more elongated bodies to a second set of grasping portions.In one implementation, a third grasping portion 228 is connected to thethird elongated body 220 with a third tapering portion 224 on the secondplane, and a fourth grasping portion 230 is connected to the fourthelongated body 222 with a fourth tapering portion 226 on the secondplane. The third grasping portion 228 is generally parallel to thefourth grasping portion 230 and the third and fourth elongated bodies220 and 222. A distance between the third and fourth grasping portions228 and 230 is larger than a distance between the third and fourthelongated bodies 220 and 222, such that the third and fourth taperingportions 224 and 226 extend inwardly from the third and fourth graspingportions 228 and 230 to the third and fourth elongated bodies 220 and222. The flexible loop of the second arm 202 is formed by a secondlooped portion 232 extending along a curve between the third and fourthgrasping portions 228 and 230.

As can be understood from FIGS. 8 and 9, which show the docked positionand the natural state of the retriever 144, respectively, in oneimplementation, the first arm 200 and the second arm 202 each form ahinge biased radially outwards from a longitudinal axis of the retriever144. When the retriever 144 is in the docked position, the first set ofgrasping portions 214 and 216 are positioned adjacent the second set ofgrasping portions 228 and 230 within the first and second planes. In thedocked position, the first and second looped portions 218 and 232 extendin opposite directions, forming a ring defining a docking space 234therebetween. The docking space 234 may be sized and shaped to match asize and shape of the docking projection 148 with the first arm 200 andsecond arm 202 adapted to matingly engage the features of the dockingprojection 148 as described herein.

In moving to the natural state, the first arm 200 and the second arm 202hinge radially outward from the longitudinal axis such that the firstset of grasping portions 214 and 216 are positioned at an angle relativeto the second set of grasping portions 228 and 230 with each at an anglerelative to the first and second planes. In one implementation, when thedocking cap 136 is retracted proximally, the ring formed by the firstand second looped portions 218 and 232 opens radially outwards to alarger diameter, thus releasing the docking projection 148.

Turning to FIGS. 10A-10B, the docking projection 148 may includefeatures adapted to matingly engage with the first arm 200 and thesecond arm 202 and the docking cap 136 to facilitate capture by theretriever 144 and to provide torque transmission. In one implementation,the leadless pacemaker 104 includes the docking projection 148 extendingfrom a surface 302 at a docking end of a body 300. The dockingprojection 148 includes one or more docking surfaces, including edgedocking surfaces 306, an end surface 308, and/or the like, configured tomatingly engage corresponding cap surfaces disposed relative to thechamber 142 of the docking cap 136, thereby providing torquetransmission to the leadless pacemaker 104. In one implementation, theedge docking surfaces 306 include one or more flat radial surfaces thatmay be radially symmetrical about the docking projection 148. The edgedocking surfaces 306 may be disposed relative to the end surface 308forming a ledge extending transverse to the end surface 308. In oneimplementation, the end surface 308 is flat and the surface 302 of thebody 300 is flat providing additional surfaces for torque transmission.

The docking surfaces may include one or more keys adapted to matinglyengage corresponding features of the docking cap 136 and/or theretriever 144. The docking projection 148 and/or the surface 302 of thedocking end of the body 300 may include one or more of the keys. In oneimplementation, the docking projection 148 includes side keys 310extending through the docking projection 148 from the surface 302 of thebody 300 to the end surface 308. The side keys 310 may be orientedrelative to each other on opposite sides, such that they are radiallysymmetric. As shown in FIG. 11, in one implementation, the side keys 310are adapted to matingly engage a portion of the first arm 200 and thesecond arm 202 of the retriever 144 in the engaged position. Forexample, the grasping portions 214, 216, 228, and 230 may be displacedduring sheathing of the docking cap 136 into the side keys 310 where thedocking cap 136 holds them in place in the engaged position. The sidekeys 310 may include one or more key surfaces 312 for torquetransmission via the first arm 200 and the second arm 202 of theretriever 144.

Similarly, the docking projection 148 may include a neck 304 indentedfrom the edge docking surfaces 306 and adapted to matingly engage atleast a portion of the first arm 200 and the second arm 202 of theretriever 144. For example, the docking cap 136 may hinge the first andsecond looped portions 214 and 232 radially inwards into the neck 304,where the docking cap 136 holds the first and second looped portions 214and 232 in compression around the docking projection 148 in the engagedposition. The indentation of the neck 304 prevents the first and secondarms 200 and 202 from translating longitudinally and disengaging fromthe docking projection 148. The geometry of the docking projection 148facilitates a smooth capture and release by the retriever 144 when thedocking cap 136 is sheathed distally or retracted proximally.

Referring to FIG. 12, the body 138 of docking cap 136 includes one ormore cap surfaces disposed relative to the chamber 142 adapted tomatingly engage the docking surfaces of the docking end of the leadlesspacemaker 104 and/or features of the retriever 144. In oneimplementation, the one or more cap surfaces include a distal endsurface 400, a proximal chamber surface 402, and one or more sidesurfaces 404 extending between the proximal chamber surface 402 and oneor more ledge surfaces 406 disposed proximal to the distal end surface400 within the chamber 142. The distal end surface 400 defines anopening into the chamber 132, and the proximal chamber surface 402defines a proximal opening 408 into the chamber 142 extending throughthe receiving portion 140. The proximal opening 408 is coaxial with thelongitudinal axis of a lumen of the torque shaft 114 and the retriever144.

The ledge surfaces 406 may mirror a size and shape of the surface 302 ofthe docking end of the body 300 of the leadless pacemaker 104. Forexample, both the ledge surfaces 406 and the surface 302 may be flat.Similarly, the proximal chamber surface 402 may be sized and shaped tomatingly engage the end surface 308 of the docking projection 148, andthe side surfaces 404 matingly engage the edge docking surfaces 306. Themating engagement of each of the various cap surfaces with thecorresponding docking surfaces provides torque transmission. When in thedocking position, the engagement of the docking projection 148 with thedocking cap 136 generates approximately 1.5 in-oz of torque with amating normal force of approximately 500 g. The torque generated is thusan order of magnitude higher than the 0.125 in-oz or less of torquegenerally needed to implant a leadless pacemaker into human tissue.

Examples of various geometries of the docking end of the leadlesspacemaker 104 are shown in FIGS. 13-18. The geometries include one ormore keys in the form of torque transmission keys, dimples, and/orgeometric interference features that matingly engage with correspondingfeatures on the docking cap 136. Turning first to FIG. 13, in oneimplementation, the surface 302 of the body 300 includes one or moreundercut keys 314 defined therein. Alternatively or additionally, thedocking projection 148 may have a cross-shape as shown in FIGS. 14A-14Cwith the side keys 310 forming angled cutouts.

In another implementation, the end surface 308 of the docking projection148 is rounded, as shown in FIGS. 15A-18. A profile of the end surface308 may have a variety of lengths from a lower profile curve to a higherdome shaped profile, each with the end surface 308 being a non-traumaticsmooth round surface. The docking cap 136 includes corresponding capsurfaces mirroring the size and shape of the end surface 308 to hold theretriever 144 in compression against the docking projection 148 in theengaged position. Frictional contact between the cap surfaces and theend surface 308 provide torque transmission. To further facilitatetorque transmission, the end surface 308 may include the keys 310adapted to matingly engage cap keys 410, as can be understood from FIGS.16A-18. To increase the friction of the mating surfaces, an overmolding412 made from silicone or a similar material may be applied to the capsurfaces within the chamber 142 and/or on the docking projection 148, asshown in FIGS. 19A-19B.

Referring to FIGS. 17A-18, the helical anchor 106 is disposed on afixing end of the leadless pacemaker 104 opposite the docking end. Inone implementation, the fixing end is at the distal end of the leadlesspacemaker 104, and the docking end is at the proximal end. It will beappreciated that some or all of these features may be reversed(stand-proud of their surface) depending on size restraints of theleadless pacemaker 104.

For a detailed description of another example of the retriever 144 inthe form of a flexible grasper and a corresponding example of thedocking projection 148, reference is made to FIGS. 20-26C. Turning firstto FIG. 20, in one implementation, the docking projection 148 includes adocking button 320 mounted to the end surface 308 with one or more posts(e.g., first and second posts 316 and 318). As can be understood fromFIG. 21, the docking button 320 may be integral with the posts 316 and318 and be a rounded surface extending between a first end 322 and asecond end 324.

As shown in FIGS. 21 and 22, the retriever 144 includes a mandrel 500connected to a base 504. The mandrel 500 may be connected directly tothe base 504 or indirectly via a retriever shaft 502. The mandrel 500extends through the proximal opening 408 and into the lumen of thetorque shaft 114. The retriever 144 may be made from a variety ofelastic or otherwise flexible materials, including, but not limited to,a polymer (e.g., polyether ether ketone (PEEK)), Nitinol or other memorywire, cable, tubing, and/or the like.

The retriever 144 includes a first arm 506 and a second arm 508extending from the base 504 and defining a docking space 514therebetween. In one implementation, the first and second arms 506 and508 form a jaw with hinges adapted to grasp at least a portion of thedocking projection 148, such as the docking button 320, in the dockingspace 514 when the docking cap 136 is sheathed over retriever 144 intothe docked position. In another implementation, one or more hinges aredisposed at the connection points between the arms 506 and 508 and thebase 504. The first arm 506 may include a first lip 510, and the secondarm 508 may include a second lip 512. Each of the lips 510 and 512extends inwardly towards a longitudinal axis of a lumen 516 of theretriever 144.

As illustrated in FIG. 23, in one implementation, a tether 518 may beintroduced during a tether mode or test mode to check for thresholds,among other reasons. The tether 518 may be, without limitation, a snare,a flexible shaft, and/or the like. For example, the tether 518 mayinclude an elongated body 520 extending distally through the lumen 516of the retriever 144 to a distal loop 522.

Turning to FIG. 24, another example of the docking cap 136 is shown. Thebody 138 of the docking cap 136 includes one or more cap surfaces, asdescribed herein, adapted to provide torque to the leadless pacemaker104 via the docking surfaces of the docking end of the leadlesspacemaker 104, as well as to move the first arm 506 and the second arm508 to the engaged position around the docking projection 148. In oneimplementation, the one or more cap surfaces are disposed relative tothe chamber 142 and are adapted to matingly engage the docking surfacesand/or features of the retriever 144. The one or more cap surfaces mayinclude the distal end surface 400, the proximal chamber surface 402,and the side surface 404 extending between the proximal chamber surface402 and the ledge surface 406, which is disposed proximal to the distalend surface 400 within the chamber 142. The distal end surface 400defines an opening into the chamber 132, and the proximal chambersurface 402 defines the proximal opening 408 into the chamber 142extending through the receiving portion 140. The proximal opening 408 iscoaxial with the longitudinal axis of a lumen of the torque shaft 114and/or the steerable catheter 118 and the lumen 516 of the retriever144.

The ledge surface 406 may mirror a size and shape of the surface 302 ofthe docking end of the body 300 of the leadless pacemaker 104. Forexample, both the ledge surface 406 and the surface 302 may be flat. Themating engagement of each of the various cap surfaces with thecorresponding docking surfaces provides torque transmission. To furtherfacilitate torque transmission, one or more of the cap surfaces mayinclude the cap keys 410. In one implementation, the cap keys 410 aredisposed radially around a distal side surface 414 extending from theledge surface 406 towards the distal end surface 400. The cap keys 410may be adapted to matingly engage corresponding side keys 310 defined inthe docking projection 148 for torque transmission.

Additional examples of the docking projection 148 are shown in FIGS.25A-25B. In one implementation, the side keys 310 are defined in theedge docking surfaces 306 of the docking projection 148 extending fromthe surface 302 of the body 300 to the end surface 308. The side keys310 may be oriented relative to each other on opposite sides, such thatthey are radially symmetric. In one implementation, the cap 136 isadapted to matingly engage the docking projection 148 with the edgedocking surfaces 306 disposed along the distal side surface 414 and thecap keys 410 disposed within the side keys 310.

The ledge surface 406 may be adapted to displace the first arm 506 andthe second arm 508 radially inward from their natural state in whichthey are biased radially outwards. In one implementation, the ledgesurface 406 displaces the first and second arms 506 and 508 until theyclose around the docking button 320 in the engaged position shown inFIG. 21. The side surface 404 holds the first and second arms 506 and508 around the docking button 320 with the first and second lips 510 and512 extending inwardly past an outer edge of the docking button 320,preventing the docking button 320 from translating distally out of thedocking space 514 and thus releasing from the retriever 144.

The docking button 320 may be mounted to the end surface 308 with thefirst and second posts 316 and 318. As can be understood from FIG.25A-25B, the docking button 320 may be integral with, connected rigidlyto, and/or connected flexibly to the posts 316 and 318. In oneimplementation, the docking button 320 is a rounded surface extendingbetween the first end 322 and the second end 324, which are separated bya gap opening into a button lumen 326. The docking button 320 includes afirst slot 328 and a second slot 330 adapted to receive and engage thefirst and second posts 316 and 318, respectively.

For a detailed description of docking and releasing the leadlesspacemaker 104 for delivery and/or retrieval, reference is made to FIGS.26A-26C. In one implementation, the retriever 144 is disposed relativeto the docking projection 148. FIG. 26A illustrates the retriever 144approaching the docking projection 148 for engagement. The dockingprojection 148 is positioned in the docking space 514 between the firstand second arms 506 and 508. For example, the docking button 320 of thedocking projection 148 may be positioned within the docking space 514,as shown in FIG. 26B. The body 138 of the docking cap 136 is sheathedover the retriever 144 until the docking end of the leadless pacemaker104 including the docking projection 148 is disposed within the chamber142. The docking cap 136 holds the retriever 144 in compression aroundthe docking button 320 locking the leadless pacemaker 104 in the dockedposition shown in FIG. 26C. The leadless pacemaker 104 is thus docked tothe catheter system 108 and prepared for delivery through the patientanatomy to the implant site, for example, within the patient heart 102.The engagement of the docking cap 136 with the docking end of theleadless pacemaker 104 may be strong enough to maintain the leadlesspacemaker 104 in the docked position against the force of gravity.

Once disposed within the implant site, the catheter system 108 isrotated using the handle body 122. The mating engagement of the one ormore cap surfaces with the one or more docking surfaces transmits thetorque of this rotation to the leadless pacemaker 104 to fix theleadless pacemaker 104 to the tissue at the implant site using thehelical anchor 106. In some implementations, the tether 518 is used tocheck for thresholds. Once the leadless pacemaker 104 is fixed in theimplant site, the catheter system 108 releases the leadless pacemaker104. In one implementation, the body 138 of the docking cap 136 isretracted proximally until the retriever 144 is outside the chamber 142,causing the first arm 506 and the second arm 508 to spring open in adirection radially outwardly, thereby releasing the docking button 320.The catheter system 108 is then retracted along the patient anatomy andremoved from the body.

During retrieval, the catheter system 108 is introduced into the bodyand advanced through the patient anatomy to the implant site until theretriever 144 is disposed relative to the docking projection 148. Theretriever 144 is advanced until the docking button 320 is positionedwithin the docking space 514 between the first and second arms 506 and508. The body 138 of the docking cap 136 is sheathed over the retriever144, locking the leadless pacemaker 104 to the catheter system 108 inthe docked position, as described herein. The catheter system 108 isthen rotated with the mating engagement of the docking projection 148with the docking cap 136 transmitting the torque to the leadlesspacemaker 104 to unfix the helical anchor 106 from the tissue. Theretriever 144 or other features of the catheter system 108, such as acutting edge, may be used to remove any tissue overgrowth on theleadless pacemaker 104. The leadless pacemaker 104 is maintained in thedocked position and the catheter system 108 is retracted through thepatient anatomy to retrieve the leadless pacemaker 104.

For another example of a docking cap adapted to lock the retriever 144in the engaged position around the docking projection 148, reference ismade to FIG. 27. In one implementation, the docking cap includes anelongated body 524 with a lumen 526 defined therein. A tether 528, whichmay be a snare, cable, or other tether, extends through the lumen 526 ofthe elongated body 526, as well as the lumen 516 of the retriever 144.The tether 528 may be looped through the docking projection 148 andtaken back to the handle body 122 of the catheter system 108.

In one implementation, the docking projection 148 of the leadlesspacemaker 104 includes the docking button 320 attached to the surface302 of the body 300 of the leadless pacemaker 104 with the post 316. Thedocking button 320 includes a flat distal surface from which a hook 332extends. The tether 528 may be looped through the hook 332.

To engage the retriever 144 in the docked position with the dockingprojection 148, the elongated body 524 is translated distally over thefirst arm 506 and the second arm 508 locking the docking button 320 inthe engaged position within the docking space 514, as described herein.To release the leadless pacemaker 104, the elongated body 526 istranslated proximally until the first and second arm 506 and 508 springradially outwards to the natural state, thereby disengaging the dockingbutton 320.

Turning to FIGS. 28 and 29, another example of the retriever 144 isshown. In one implementation, the retriever 144 includes a retrieverbase 600 from which a set of arms 602, including a first arm disposedopposite a second arm around a central lumen 604, extends. In oneimplementation, the set of arms 602 are disposed on and/or integral witha retriever shaft 606 extending through the retriever base 600. Thecentral lumen 604 extends through the retriever shaft 606, the retrieverbase 600, and through the set of arms 602.

The set of arms 602 are biased radially inwards towards the centrallumen 604 in a natural state. In one implementation, a mandrel 608 istranslated within the central lumen 604 to move the set of arms 602between an engaged and disengaged position with the docking projection148. More particularly, the docking projection 148 may include a dockingsurface opening 334 defined within a docking surface 336 extending fromor otherwise part of the surface 302 of docking end of the body 300 ofthe leadless pacemaker 104. The set of arms 602 include a first tab 610and a second tab 612 each extending radially outwards from the centrallumen 604. In the disengaged or natural state, the set of arms 602 arebiased radially inwards, such that the set of arms 602 may be advancedthrough the docking surface opening 334. The mandrel 608 is advanceddistally through the central lumen 604 pushing the set of arms 602 apartelastically, such that the first tab 610 and the second tab 612 aredisplaced radially outwards, thereby engaging the edges defining thedocking surface opening 334 and locking the retriever 144 to the dockingprojection 148.

To disengage the retriever 144 from the docking projection 148 torelease the leadless pacemaker 104, the mandrel 608 is retractedproximally within the central lumen 604, causing the set of arms 602 tospring radially inwards to the natural state. The first and second tabs610 and 612 thus disengage the edges defining the docking surfaceopening 334, permitting the catheter system 108 to be retracted.

For a detailed description of examples of the retriever 144 in the formof a snare loop, reference is made to FIGS. 30A-40. Turning first toFIGS. 30A-30B, in one implementation, the body 138 of the docking cap136 is fixed to a component of the catheter system 108, such as thetorque shaft 114. The chamber 142 of the docking cap 136 is coaxial witha lumen of the catheter system 108, including, for example, a lumen ofthe torque shaft 114.

In one implementation, the retriever 144 includes a first sheath 702 anda second sheath 704 extending distally from the chamber 142. The firstand second sheaths 702 and 704 may extend through the chamber 142proximally into the lumen of the catheter system 108. The first andsecond sheaths 702 and 704 each translate longitudinally through thechamber 142 and the lumen of the torque shaft 114.

A snare 700 extends distally from and is translatable within the firstand second sheaths 702 and 704. The snare 700 is configured to movebetween an engaged and disengaged position to releasably engage thedocking projection 148. The first and second sheaths 702 and 704 may bemade from a variety of materials, including, but not limited to, steel,elastic cable tubes, braided or coiled Polytetrafluoroethylene (PTFE)impregnated polyimide tubes, and/or the like. The snare 700 may be madefrom a variety of flexible materials, such as Nitinol or other elasticmaterials.

Turning to FIGS. 31A and 31B, in one implementation, the snare 700extends from and is translatable within a first snare lumen 710 of thefirst sheath 702 and a second snare lumen 712 of the second sheath 704.The snare 700 moves between the engaged and disengaged positions withinthe first and second snare lumens 710 and 712 to capture and release thedocking projection 148 of the leadless pacemaker 104. In oneimplementation, the first sheath 702 includes a first end coil 706, andthe second sheath 704 includes a second end coil 708. Radiopacity may beobtained by making the first and second end coils 706 and 708radiopaque. Alternatively or additionally, a NiTi DFT composite wirecombining Nitinol with Titanium or Platinum in varying sheath-to-coreratios, a Tungsten or Tantalum strand in NiTi cable, and/or the like maybe used for radiopacity. Further, radiopaque coils and/or marker bandsmay be crimped or otherwise attached to the snare 700, radiopaque coilsmay be wound around an NiTi core, and/or the like.

In one implementation, the snare 700 includes a first snare wire 714 anda second snare wire 716. The first snare wire 714 extends from the firstsnare lumen 710 into the second snare lumen 712 forming a first snareloop pointing in a first direction, and the second snare wire 716extends from the first snare lumen 710 into the second snare lumen 712forming a second snare loop pointing in a second direction. In oneimplementation, the first direction is different from the seconddirection, forming a docking space therebetween. The first direction maybe oriented relative to the second direction such that the snare 700forms a duckbill shape.

As can be understood from FIGS. 32-36, to engage the docking projection148 and lock the leadless pacemaker 104 in the docked position with thecatheter system 108, the docking space formed by the snare 700 isdisposed relative to at least a portion of the docking projection 148,such as the docking button 320, as shown in FIG. 32. The snare 700 isthen advanced distally over the leadless pacemaker 104 until the dockingprojection 148 is disposed in the docking space. For example, the firstsnare loop and the second snare loop are advanced distally until thedocking button 320 is disposed in the docking space of the snare 700, asshown in FIG. 33A. The snare 700 may be advanced by advancing thecatheter system 308, the snare 700, and/or the first and second sheaths702 and 704. The first and second sheaths 702 and 704 are translatablethrough the docking cap 136, and the first snare wire 714 and the secondsnare wire 716 are each translatable within the first snare lumen 710and the second snare lumen 712.

The snare 700 is moveable from the disengaged position to the engagedposition, shown in FIGS. 33B and 34, by translating the first snare wire714 and the second snare wire 716 proximally within the first snarelumen 710 and the second snare lumen 712. Stated differently, the firstand second snare wires 714 and 716 are each retracted into the first andsecond snare lumens 710 and 712. The proximal translation of the firstand second snare wires 714 and 716 tightens the snare 700, closing thefirst and second snare loops into smaller loops. Stated differently, apeak of each of the snare loops formed by the first snare wire 714 andthe second snare wire 716 moves proximally towards a distal end of thefirst and second sheaths 702 and 704 decreasing a size of each of thesnare loops. Additionally, the peaks of the snare loops formed by thefirst snare wire 714 and the second snare wire 716 simultaneously movetowards each other and a central axis of the docking space during theproximal translation of the first and second snare wires 714 and 716.The movement of the peaks radially inwards towards each other and thecentral axis decreases a size of the docking space and tightens thefirst and second snare wires 714 and 716 around at least a portion ofthe docking projection 148, thereby locking the docking projection 148in the engaged position. For example, as shown in FIGS. 33B and 34, thesize of the docking space may be decreased until the first and secondwires 714 and 716 close around the first and second posts 316 and 318and/or the size of the docking space is smaller than a size of thedocking button 320.

The snare 700 captures and locks the docking projection 148 in theengaged position with a freedom of movement of the leadless pacemaker104. More particularly, as shown in FIG. 35, the engagement of the snare700 with the docking projection 148 provides a junction that permitsmovement of the leadless pacemaker 104 relative to a longitudinal axisof extending through the chamber 142 and/or one or more lumens of thecatheter system 108. The movement may be parallel or at an angle to thelongitudinal axis without releasing the leadless pacemaker 104 from thecatheter system 108. For example, as shown in FIG. 35, the junction mayact like a hinge allowing the repositioning of the leadless pacemaker104 without release.

Once the snare 700 is in the engaged position with the dockingprojection 148, to move the leadless pacemaker 104 to the dockedposition with the catheter 108, as shown in FIG. 36, the first sheath702 and the second sheath 704 are retracted proximally until the dockingprojection 148 is disposed within the chamber 142 of the docking cap136. In the docked position, the leadless pacemaker 104 may be movedthrough the patient anatomy to and/or from the implant site. Duringretrieval, the snare 700 and/or other features of the retriever 144 mayinclude a cutting edge or similar mechanism for removing tissueovergrowth on the leadless pacemaker 104. Further, the retriever 144 maybe used in a tether and/or test mode, for example, to test forthresholds by advancing the first and second sheaths 702 and 704 alongwith the first and second snare wires 714 and 716, such that the dockingprojection 148 remains engaged with the snare 700.

For a detailed description of the interaction of the retriever 144 withthe docking cap 136, reference is made to FIGS. 37-40. In oneimplementation, the body 138 of the docking cap 136 includes one or morecap surfaces, as described herein, adapted to provide torque to theleadless pacemaker 104 via the docking surfaces of the docking end ofthe leadless pacemaker 104. In one implementation, the one or more capsurfaces are disposed relative to the chamber 142 and are adapted tomatingly engage the docking surfaces and/or features of the retriever144. The one or more cap surfaces may include the distal end surface400, the proximal chamber surface 402, and the side surface 404extending between the proximal chamber surface 402 and the distal endsurface 400. The distal end surface 400 defines an opening into thechamber 132, and the proximal chamber surface 402 defines the proximalopening 408 into the chamber 142 extending through the receiving portion140. The proximal opening 408 may be coaxial with the longitudinal axisof a lumen of the torque shaft 114 and/or the steerable catheter 118 andthe central axis of the snare 700.

The mating engagement of each of the various cap surfaces with thecorresponding docking surfaces provides torque transmission. To furtherfacilitate torque transmission, one or more of the cap surfaces mayinclude the cap keys 410. In one implementation, the cap keys 410 aredisposed radially around the side surface 404, for example, on radiallyopposite sides of the longitudinal axis. The cap keys 410 may be adaptedto matingly engage corresponding side keys 310 defined in the dockingprojection 148 for torque transmission, as described herein.

In one implementation, the docking cap 136 further includes one or moretrackers corresponding to the one or more sheaths of the retriever 144.For example, the docking cap 136 may include a first tracker 416corresponding to the first sheath 702 and a second tracker 418corresponding to the second sheath 704. In one implementation, the firstand second trackers 416 and 418 maintain the first and second sheaths702 and 704 in an orientation relative to each other and to the centeraxis coaxial with the longitudinal axis running through the proximalopening 408. The orientation may include, for example, the first sheath702 maintained in a position radially opposite the second sheath 704about the center axis. Stated differently, the first and second sheaths702 and 704 may be disposed approximately 180 degrees apart about thecenter axis.

The first and second sheaths 702 and 704 are translatable within thefirst and second trackers 416 and 418, respectively. In oneimplementation, the first tracker 416 includes a first tracker lumen 420within which the first sheath 702 is translatable, and the secondtracker 418 includes a second tracker lumen 422 within which the secondsheath 704 is translatable, as shown in FIGS. 38-40. The first andsecond trackers 416 and 418 thus maintain the first and second sheaths702 and 704 in an orientation adapted to position the snare 700 forcapturing the docking projection 148 such that it can be moved into thechamber 142 into the docking position by retracting the first and secondsheaths 702 and 704 into the lumen of the torque shaft 114.

In one implementation, the docking button 320 is mounted to the dockingprojection 148 with a set of docking balls fixed to the first and secondposts 316 and 318, as shown in FIGS. 39-40. The first post 316 mayextend between a first proximal ball 336 and a first distal ball 340.The first proximal ball 336 is disposed in the first slot 328, and thefirst distal ball 340 extends through an opening in the end surface 308,thereby mounting the docking button 320 to the docking projection 148with the first post 316. Similarly, the second post 318 may extendbetween a second proximal ball 338 and a second distal ball 342. Thesecond proximal ball 338 is disposed in the second slot 330, and thesecond distal ball 342 extends through another opening in the endsurface 308, thereby mounting the docking button 320 to the dockingprojection 148 with the second post 318. In one implementation, thefirst post 316 is mounted to the docking projection 148 and the dockingbutton 320 such that it is radially symmetric with the second post 318.

It will be appreciated that the retriever 144 may be displaced to engagethe docking projection 148 using the docking cap 136 as describedherein. Additionally or alternatively, a push-pull actuator 826 may beused to cause the retriever 144 to engage and disengage the dockingprojection 148. For example, turning to FIGS. 41-46, in oneimplementation, the retriever 144 is in the form of a hinged grasper anddisplaceable between the engaged and disengaged position with apush-pull actuator 826.

Referring first to FIGS. 41-43, in one implementation, the leadlesspacemaker 104 includes the docking projection 148 extending from thesurface 302 at the docking end of the body 300. The docking projection148 includes a projection 800 defining a slot 802. In oneimplementation, the projection 800 has a length extending in a firstdirection across the surface 302, such that the length is approximatelythe same as a diameter of the surface 302, and the projection 800 has anarrow width extending in a second direction across the surface 302,with the width being less than the diameter of the surface 302.

The projection 800 includes one or more docking surfaces defining theslot 802 and configured to matingly engage corresponding features of theretriever 144, thereby providing torque transmission to the leadlesspacemaker 104. In one implementation, the retriever 144 in the form ahinged grasper is formed with a first arm 804 and a second arm 806. Afirst grasping portion 808 is disposed at a distal end of the first arm804 and includes a first cutout 812. Similarly, a second graspingportion 810 is disposed at a distal end of the second arm 806 andincludes a second cutout 814.

The first cutout 812 and the second cutout 814 collectively define adocking space 816 adapted to engage the projection 800. Morespecifically, to engage the leadless pacemaker 104 in the engagedposition, lips of the grasping portions 808 and 810 extend into the slot802 with a proximal portion of the projection 800 disposed in thedocking space 816, thereby gripping the docking projection 148 with theretriever 144. The first arm 804 and the second arm 806 move radiallyoutwardly into the disengaged position and the grasping portions 808 and810 release the projection 800, widening the docking space 816. In oneimplementation, the first arm 804 and the second arm 806 each taper inwidth proximally from the grasping portions 808 and 810 to a base 818.

To move the arms 804 and 806 between the engaged and disengagedpositions, the push-pull 826 actuator is translated relative to thedocking cap 136 within the chamber 142. The push-pull actuator 826 mayextend through and be translated within a lumen of the torque shaft 114.In one implementation, the push-pull actuator 826 includes a neck 824extending distally from a body of the push-pull actuator 826. The neck824 includes one or more knobs 822 extending radially outwardly from alongitudinal axis of the push-pull actuator 826. The neck 824 isdisposed within a gap 824 defined in each of the first arm 804 and thesecond arm 806, and each of the knobs engage corresponding tracks 820 ineach of the arms 804 and 806. One or more hinge pins 828 extend throughholes in the docking cap 136 and the arms 804 and 806 to rotationallymount the retriever 144 to the docking cap 136. Engagement of the knobs822 with the arms 804 and 806 within the tracks 820 causes the push-pullactuator 826 to displace the arms 804 and 806 radially inwardly andoutwardly relative to a rotational axis of the hinge pin(s) 828 when thebody of the push-pull actuator 826 is translated distally andproximally.

Similarly, turning to FIGS. 44-46, the first arm 804 and the second arm806 are displaceable between the engaged and disengaged position withthe push-pull actuator 826. In one implementation, the dockingprojection 148 includes one or more docking surfaces, including edgedocking surfaces 306 and/or the like, configured to matingly engagecorresponding features of the first arm 804 and the second arm 806,thereby providing torque transmission to the leadless pacemaker 104. Thedocking surfaces 306 may form a hexagonal shape or other polygonal shapeof the docking projection 148. The first arm 804 may include a firstdocking surface 832, and the second arm 806 may include a second dockingsurface 834. Each of the first and second docking surfaces 832 and 834may be planar or other shapes mirroring a shape of the edge dockingsurfaces 306.

The first docking surface 832 and the second docking surface 834 areadapted to engage one or more of the edge docking surfaces 306 of thedocking projection 148. More specifically, to engage the leadlesspacemaker 104 in the engaged position, first docking surface 832 and thesecond docking surface 834 are pressed against the edge docking surfaces306, thereby gripping the docking projection 148 with the retriever 144.The first arm 804 and the second arm 806 move radially outwardly intothe disengaged position and the grasping portions 808 and 810 releasethe docking projection 148.

The foregoing merely illustrates the principles of the presentlydisclosed technology. Various modifications and alterations to thedescribed implementations will be apparent to those skilled in the artin view of the teachings herein. It will thus be appreciated that thoseskilled in the art will be able to devise numerous systems, arrangementsand methods which, although not explicitly shown or described herein,embody the principles of the presently disclosed technology and are thuswithin the spirit and scope of the present presently disclosedtechnology. From the above description and drawings, it will beunderstood by those of ordinary skill in the art that the particularimplementations shown and described are for purposes of illustrationsonly and are not intended to limit the scope of the present presentlydisclosed technology. References to details of particularimplementations are not intended to limit the scope of the presentlydisclosed technology.

What is claimed is:
 1. A catheter system, comprising: a catheter havinga lumen along a longitudinal axis; a docking cap coupled to the catheterand including a body having a side surface defining a chamber, and aproximal opening coaxial with the longitudinal axis and extending intothe chamber, wherein the docking cap includes a first cap key and asecond cap key disposed radially around the side surface; a retrieverincluding a first sheath having a first snare lumen and a second sheathhaving a second snare lumen, wherein the first sheath and the secondsheath extend distally through the proximal opening and the chamber; anda plurality of snare loops extending distally within the first sheathand the second sheath through the proximal opening and the chamber in anengaged position and a disengaged position, wherein a first snare wireand a second snare wire extend longitudinally through the first snarelumen at a first radial position between the first cap key and thesecond cap key, wherein the first snare wire and the second snare wireextend longitudinally through the second snare lumen at a second radialposition radially between the first cap key and the second cap key andopposite to the first radial position, wherein the first snare wireextends from the first snare lumen into the second snare lumen to form afirst snare loop of the plurality of snare loops pointing in a firstdirection, wherein the second snare wire extends from the first snarelumen into the second snare lumen to form a second snare loop of theplurality of snare loops pointing in a second direction different fromthe first direction, and wherein the first snare loop and the secondsnare loop form a docking space and the plurality of snare loops aremovable between the engaged position and the disengaged position bytranslating the first snare wire and the second snare wire within thefirst snare lumen and the second snare lumen to change a size of thedocking space.
 2. The catheter system of claim 1, wherein the firstsheath and the second sheath are each translatable within the chamberand the proximal opening.
 3. The catheter system of claim 1, wherein afirst portion of the first sheath having the first snare lumencontaining both the first snare wire and the second snare wire isdisposed at the first radial position radially opposite to a secondportion of the second sheath having the second snare lumen containingboth the first snare wire and the second snare wire at the second radialposition.
 4. The catheter system of claim 1, wherein a junction betweenthe plurality of snare loops and a docking projection of a leadlesspacemaker in the engaged position permits movement of the leadlesspacemaker relative to the longitudinal axis.
 5. The catheter system ofclaim 4, wherein the movement of the leadless pacemaker relative to thelongitudinal axis includes at least one of movement parallel to thelongitudinal axis or at an angle relative to the longitudinal axis. 6.The catheter system of claim 1, wherein the docking cap includes a firsttracker and a second tracker disposed in the chamber, wherein the firstsheath extends through and is translatable within the first tracker atthe first radial position, and wherein the second sheath extends throughand is translatable within the second tracker at the second radialposition.
 7. The catheter system of claim 1, wherein the first cap keyand the second cap key are configured to provide torque transmission bymatingly engaging one or more docking surfaces of a docking projectionof a leadless pacemaker.
 8. The catheter system of claim 7, wherein thedocking projection includes a docking button.
 9. A catheter systemcomprising: a docking cap including a body having a side surfacedefining a chamber, and a proximal opening extending into the chamber,wherein the docking cap includes a first cap key and a second cap keydisposed radially around the side surface; a retriever including a firstsheath having a first snare lumen and a second sheath having a secondsnare lumen, wherein the first sheath and the second sheath extenddistally through the proximal opening and the chamber; and a pluralityof snare loops extending distally within the first sheath and the secondsheath through the proximal opening and the chamber in an engagedposition and a disengaged position, wherein a first snare wire and asecond snare wire extend longitudinally through the first snare lumen ata first radial position between the first cap key and the second capkey, wherein the first snare wire and the second snare wire extendlongitudinally through the second snare lumen at a second radialposition radially between the first cap key and the second cap key andopposite to the first radial position, wherein the first snare wireextends from the first snare lumen into the second snare lumen to form afirst snare loop of the plurality of snare loops having a first peak atthe central axis, wherein the second snare wire extends from the firstsnare lumen into the second snare lumen to form a second snare loop ofthe plurality of snare loops having a second peak at the central axis,and wherein the plurality of snare loops are movable between the engagedposition and the disengaged position by translating the first snare wireand the second snare wire within the first snare lumen and the secondsnare lumen, the translation of the first snare wire and the secondsnare wire moving the first peak radially inwards toward the second peakto the engaged position and radially outwards away from the second peakto the disengaged position.
 10. The catheter system of claim 9, whereineach of the first sheath and the second sheath includes an end coil. 11.The catheter system of claim 10, wherein each of the end coils isradiopaque.
 12. The catheter system of claim 9, wherein the docking capincludes a first tracker and a second tracker disposed in the chamber,wherein the first sheath extends through and is translatable within thefirst tracker at the first radial position, and wherein the secondsheath extends through and is translatable within the second tracker atthe second radial position.
 13. The catheter system of claim 9, whereinthe first snare loop and the second snare loop form a docking space, thedocking space having a smaller size in the engaged position than in thedisengaged position.
 14. The catheter system of claim 9, wherein thefirst snare wire and the second snare wire are tightened around adocking projection of a leadless pacemaker disposed within the dockingspace in the engaged position.
 15. The catheter system of claim 14,wherein the docking projection is receivable within the chamber.
 16. Thecatheter system of claim 9, wherein each of the first snare wire and thesecond snare wire are attached to at least one mandrel.
 17. A method forengaging a leadless catheter, the method comprising: disposing a dockingspace relative to a docking projection extending from a surface of abody of a leadless pacemaker, the docking space formed by a plurality ofsnare loops extending distally within a first sheath and a second sheaththrough a proximal opening and a chamber of a docking cap in an engagedposition and a disengaged position, wherein a first snare loop of theplurality of snare loops points in a first direction and a second snareloop of the plurality of snare loops points in a second directiondifferent than the first direction, wherein the first snare loop isformed from a first snare wire extending from a first snare lumen of thefirst sheath into a second snare lumen of the second sheath, wherein thesecond snare loop is formed from a second snare wire extending from thefirst snare lumen of the first sheath into the second snare lumen of thesecond sheath, wherein the first snare wire and the second snare wireextend longitudinally through the first snare lumen at a first radialposition between a first cap key and a second cap key of the dockingcap, wherein the first snare wire and the second snare wire extendlongitudinally through the second snare lumen at a second radialposition radially between the first cap key and the second cap key andopposite to the first radial position, and wherein the first cap key andthe second cap key are disposed radially around a side surface of a bodyof the docking cap defining the chamber; advancing the first snare loopand the second snare loop over the leadless pacemaker until the dockingprojection is disposed in the docking space in the disengaged position;decreasing a size of the docking space by retracting the first snarewire and the second snare wire into the first snare lumen and the secondsnare lumen until the first snare wire and the second snare wire tightenaround the docking projection in the engaged position; and retractingthe first sheath and the second sheath into a lumen of a catheter untilthe docking projection is positioned within the chamber radially betweenthe first cap key and the second cap key of the docking cap.
 18. Themethod of claim 17, wherein the docking cap includes a first tracker anda second tracker disposed in the chamber, the first sheath retractablealong the first tracker at the first radial position between the firstcap key and the second cap key and the second sheath retractable alongthe second tracker at the second radial position between the first capkey and the second cap key.
 19. The method of claim 17, furthercomprising: retrieving the leadless pacemaker by translating thecatheter.
 20. The method of claim 17, further comprising: delivering theleadless pacemaker by translating the catheter.